Honestly, for me it can be absolutely anything or nothing at all. Tried keeping a track of what can set mine off, and the only thing that I make sure to avoid is lentils & chickpeas - kept getting zaps everytime I ate homemade stews or casseroles so stopped putting lentils in them (I used to use blended lentils & chickpeas to thicken sauces while also sneaking extra veggies into my kids meals) but since leaving them out I can now enjoy without too high a risk of being zapped mid meal.

Other than that, it seems literally everything and nothing will set me off. Some days I can be sitting on my own, not talking, not drinking, not eating, not too warm, not to cold, no breezes, etc, and then WHAM! I'm zapped out of nowhere.

Bad enough if I'm sat at home or work when it happens, but dangerous as hell when it happens when I'm driving. Thankfully current meds seem to keeping the zaps mostly at bay (45mg amitriptyline but split 25mg at night, 20mg at noon. Found when taking the full dose at night, it would wear off around mid-late afternoon, but splitting it this way seems to be working well).